In the past it has been necessary, in order to obtain access to obstructed fasteners, to use an extensive number of specially designed tools, each capable of negotiating a particular obstruction, but generally not adaptable to a more versatile use. In the automotive and aircraft industries especially, new structures and assemblies include new obstructions and relatively inaccesible nuts and bolt heads for which new tools must be devised. The capital outlay for the many such tools which are necessary, plus the space needed for storing them, are large and many repair facilities have found the requirements for such tools to be quite burdensome.